Secret-service cord circuits



Dec. 19, 1922. 1,439,071.

H. D. CURRIER.

SECRET SERVICE CORD CIRCUITS.

ORIGINAL FILED MAR. 20,1915.

Z/ Z/z' 72725525.: ZZZ/E2770]? 15 2232775 zzPzZEP. WQ

idatented Dec. llll, with.

HTRAM SD. CUEBTElt, Oil GHTCAGG', ILLINOIS, ASSTGNOR TQ KELLQGG SWITCHBOARD AND SUPPLY GOMPANY, 01E CHICAGG, ILLEINQIS, A CORPORATION G1" ILLINOIS.

EGEET-SEEVIGE CURE CIRCUEEe.

application filed March 20,1915, Serial No. ,835. Renewed March it, 1920. Serial No. 864,872.

To allwhom it may concerm. 4

.Be it known that l, HlRAM D. Gunman, a citizen of the United States of America, residin in Chicago, county of Cook, and State of ll inois, have invented certain new and -useful Improvements inSecret-Service Cord Circuits, of which the following is a specii'ication.

My invention relates to telephone systems in which link or cord circuits are employed and has to do morecparticularly with socalled multiple line lamp systems in which instantaneous disconnect and recall are provided, and has for its object a new and improved system of the above character. Tn systems heretofore used it has been cus ternary to reoperate the multiple line signals associated with the line circuit of the-calling subscriber when the subscriber wished to initiate a recall. in systems of this kind,

it is possible for any idle operator to answer the recall. it has been found desirous to have the operator who handled the original call, also handle the recall; she can. very often handle it more readily and more in telligently than the other operators. There;-

iore, l have arranged to segregate the recall to the original operators position. To 510- complish' this, it provide means by which when a subscriber recalls, one movement of the switch-hook under the control of the recalling subscriber is suilicient to star-tin operation certain instrumentalities which convey to the operator an intermittent signal similar to the signal that rnight be conveyed by the flashing of the switch-hook.

Another object of my invention is the pro.- vision or" an absolute secret service system. In systems heretofore in use, in which automatic listening is provided, it has been possible for a second-operator to listen in on an established connection by operating her apparatus in a certain manner. T have overcome this objection by providing'a system in. which it is impossible, for a second operator to listen in. These and other objects of my invention will be more particularly "pointed out in the following specification and claims.

For a better understanding of my inven tion, reference maybe had to the accompanying drawing in which is shown the common battery substations A. and B termihating in the central office in line circuits l1 and l respectively. The common battery line circuit A consists of a double wound line relay LR, cut-ofirelay GO, ,theniultiple line lamps'S and multiple jacks J. The

left hand- .winding is of a comparatively low resistance, the reasons for having these windings of different resistances will hereinatter appear. The line circuit as illustrated is known as a multiple lamp line circuit in which the lamps S and jacks J appear before a number-of operators so that any one operator may answer a call to the exclusion or the other operators. The substation E and the line circuit L are similar in allrespects to the substation A and line circuit L, except that the substation B is one of a plurality of like substations which are connected to the line conductors leading to the central office equipment.

The cord circuit C comprises the: answering plug AP and calling plug GP, the two plugs being connected-by the heavily marked conductors of the cord circuit and having the condensers K and K interposed. Associated with the answering end of the cord circuit is the answering sleeve supervisory relay AS and the answering tip supervisory circuit of the answering sleeve supervisory relay AS,,/which relay controls the connection or the operators telephone set 0 to the strands of the cord circuit. The test relay TR- comprises a pair of windings, one a comparatively high resistance winding 8 and the other a comparatively low resistance windin 6. I also provide a link disconnect relay L for making possible instantaneous disconnect and recall, and a recall relay Bill for segregating a recall to the particular bperator that previously answered the original call. Associated with the calling end of the cord circuit 1 provide a calling tip super visory relay CT and a calling sleeve supervisory rela CS for controlling the circuit of the callmg supervisory lamp CL. The calling sleeve supervisory relay C also controls the disconnection of the operators set 0 from the strands of the cord circuit. A party line ringing key Eli is provided for connecting one of a plurality of generators to the common ringing lead 2 and for controlling the ringing control relay BC. The ringing control relay RC controls the ringact are

ing interrupter relay RI, which through the medium of the interrupter I applies ringf ing current from the common lead 2 to the line of the called subscriber.

tering device comprising a'meter magnet MM and a meter control relay MR.

Assuming that the subscriber at the substation A wishes to initiate a call, upon the removal of the receiver thereat, a circuit is closed through the line relay LR, the. line relay upon energizing closes a circuit through the multiple line lamps S. An operator upon noting theline lamp S glowing inserts the answering plug AP-mto a jack J of the calling line. Upon the insertion of the answering plug AP into-the jack J, an ener izing circuit is closed through cut-oil re ay CO and through the high resistance winding of the relay TR. This circuit extends from battery through the high winding of said test relay, norv and through the Winding of the said cut-off mal contact 3 of the linkdisconnect relay LD, through the sleeve contacts'of theiplug AP andjack J and through the. cut-o re, lay CO to ground. The cut-ofi' relay GO upon energizing, disconnects thesubscribers line circuit from the line relay LRtherebyy causing the line lamps S to be e'fia'ced. Thetest relay TR, upon energizing, .closes-the tip strand of the cordcircuit at itscontact--f and thereby closes an energizingjcircuib through the answering tip supervisory re lay AT. The answering tip supervlsorylralay AT, upon energizing, prevents the pre-', mature glowing of the answering super visory lamp AL by opemn its normal con-.

tact 5 and also prevents t e closing of an energizing circuit for link disconnect relay LD. A further result due to the energiza tion of the test relay TB is the closing of a multiple circuit, through its locking 'wlnding 6 and through the answering sleeve supervisory relay AS to the sleeve conductor of the answering plug AP. 'Th1s 'c1r cu-1t extends from battery through the wlnclmgs "of the answering 'sleevesupervisory relay AS and the locking. winding 6 of the test relay TR to the contact 7 of the said test relay TR, then throughthe normal'contact 3 of the link disconnectjrelay. LD, through the sleeve conductor of the answering plug AP and jack J, and through the cut-off relay ground. This low resistance path, extending to the sleeve conductor of multiple jacks J, prevents'the test relay TB of another cord circuit from operatively energizing and connectingthe operators set of the said second cord circuit to the line on cuit ot the calling subs'criberJ Answering sleeve supervisory relay AS, u onenergizing, connects the operators set to the cord circuit through its alternate contacts 9 and 10 and through the normal contacts 11 and 12 or the calling sleeve supervisory relay 15.

Associated with the cord circuit C is a service regis-f' called subscriber and if 'it is idle she then 1 inserts the callin'gplug CP into the jaclc The operator, now being in -connection With is-wanted, the operator tests the line of the J connected to the line circuit of the called subscriber. If the'line of the called 'subscrlber is busy, the operator will receive the usual busy click in her receiver notifying herof the condition of the called line,

and will thereupon notify the calling subscriber that the called. line is busy. Upon .the insertion ,of the calling plug CP'into the jack J an energizing circuit is 'closed through the calling sleeve supervisory relay CS and the cut-oif relay C0 of the called line. (This circuit extends from .battery through the winding of the said calling sleeve supervisory relay'CS, sleeve .conducto'rof the calling plug CP and jack J relay {CO to ground. The relay CO upon energizing, disconnects the line relay LR frolnthe line circuit of theicalled subscriber; vThe calling sleeve supervisory relay, upon 'ene'rglz'mg, d sconnects the operators set, 0 from the strands ofthe cord circuit at its contacts 11 and 12 and closes a circuit through the calling; supervisory lamp CL at. its; contact-13. The circuit for lamp CL extendsfrom battery through the saidcall- 'ing l amp 'CIl, end-contact 14 of ringing key RK; normal'contact 16 of ringing controlv calling lamp CL is the customary supervisory lamp for indicating to the operator when the'called subscriber responds. The operator next depresses, one of theringing key plungers to connect one of the generators to the common ringinglead 2, to initiate the operation of the automatic ringing equipment, and to close a circuit "tor the meter control relay MR. The circuit for the meter control relay vMlhl, extends from battery through the winding of said relay MR, alternate contact 14 of ringing key BK, normal contact 16 ofringing control relay RC, normal contact 17 of link disconnect relay Ll), normal contact 18 of the tip supervisory relay CT and 'through the alternate contact 13 of the callingsleeve supervisory relay GS to ground. The meter relay MR, upon energizing, closes a circuit through the magnet MM Which-then operates to register a call upon the service meter. W hen the operator releases the pressure from the plunger of the ringing key RK, the end springs 14 and 15 return to their normal position. The closing control relay' closes a locking circuit for itself at its alteriii arsenal cuit through the ringing control relay BC. This circuit extends from battery through the winding of said relay RC, alternate contact of the end springs 15, normal contact 18 of the calling tip supervisory relay CT andthrough the alternate contact 13 of the calling sleeve supervisory relay GS to ground. The ringupon energizing,

nate contact 16 independent of the end spring 15, closes a circuit through the interrupter relay RI and separates the talking strands of the calling end of the cord circuit from the strands of the answering end of the cord circuit. The said locking circuit for ringing control relay RC extends from battery through thewinding of said relay, through its alternate contact 16, through normal contact 17 of link disconnect relay LD, normal= contact 18 of calling tip supervisory relay CT and through alternate contact 13 of calling sleeve supervisory relay CS to ground. The circuit for the interrupter relay RT extends trom battery through the interrupter I, through the winding of said relay RT, through alternate. contact 20'of the ringing control relay RC to ground. The ringing relay RT, upon energizing, connects ringin current from common ringing lead 2 to the line of the called subscriber. I

Upon the response of the called subscriber, a circuit 'is closed through the calling tip supervisory relay CT, this circuit extends from battery through the lower winding of said relay'CT, normal contact 21 of ringing relay RI, ring contact of the calling plug GP and jack J through the substation 1B, tip contacts of the jack J and plug OP, normal contact 22 of ringing relay RI, alternate contact 23 of relay CS, and through the upper winding of the calling tip supervisory relay CT to ground. The relay CT, upon -energizing-, opens the locking circuit for the ringing control relay RC and for the supervisory lam-p CL at its contact18. The ringing control relay, upon de-energizing, opens the circuit of the ringing interrupter relay RT at its contact 20 and connects the strands of the calling and called ends of the .cord circuit, so that conversation may now take place between the calling and called subscriber over the heavily marked conductors. The efiacement of the calling. lamp CL indicates to the operator that the called party has responded.

ssuming now that conversation has been finished, the subscriber at thesubstation A, upon replacing the receiver upon its switchhook, opens the energizing circuit of the answering tip supervisory relay AT at'the switch-hook contacts. The supervisory relay AT, upon de-energizing, closes an energizing circuit for the link disconnect relay LD at its contact 5 and closes a locking circuit for the test relay-TR and for the sleeve supervisory relay AS .at its contact 26. The locking circuit for the sleeve supervisory relay AS extends from battery through the winding of said relay, its alternate contact 27,

normal contact 26 of relay AT, alternate contact 28 of relay AS and alternate contact 13 of relay CS toground. The locking circuit for the test relay TR extends from battery through the windings of said relay,

alternate contact 27 of relay AS, normal contact 26 of relay AT, alternate contact 28 of relay AS and alternate contact 13 of relay CS to ground. A further result due to the de-energization of the answering tip supervisory relay AT is the closing of a circuit through the answering supervisory lamp AL. This circuit extends from battery through the said lamp AL, normal contact 29 of relay RR, normal contact 5 of relay AT, alternate contact 28 of relay AS and alternate contact 13 of relay CS to ground. The circuit for the link disconnect relay-Ll) extends from battery through the-winding of said relay, normal contact 5 of relay AT, alternate contact 28 of relay AS and alternate contact 13 of relay US to ground. The link disconnect relay LD, upon energizing,

g disassociates the talking strandsof the link circuit from the line circuit, opens the circuit of the cut-off relay CO at its normal contact 3 and connects the control relay OR to the sleeve of the answering plug AP. The called subscriber B, upon replacing his receiver upon the receiver hook, opens the circuit of the calling tip supervisory relay CT at the switch-hook contacts. The supervisory relay CT, upon de-energizing, closes a I circuit for the calling supervisory lamp CL. The circuit for the calling supervisory lamp extends from battery through the said lamp, alternate contact 17 of link disconnect relay LD, normal con-tact 18 of relay CT and'alternate contact 13 of relay C5 to ground. The operator, upon noting the glowing of the answering supervisory lamp AL and the tltl Mill

llti) callingsupervisory lamp CL, .removes the answering plugAP and the calling p GP from their respective jacks J an J The removal of the calling plug GP from the jack J allows the cut-off relay (5G and the calling sleeve supervisory relay CS to deenergize. The relays C'S- upon de-energiz ing, opens the lOCkll'lg circuit for the link disconnect relay Ll), answering sleeve supervisory relay AS, test relay TR and for the supervisory lamps CL and AL. The relays, upon de-energizing permit the apparatus of the cord circuit to return to normal as soon as the answering plug APis removed from the jack J.

Should-the calling subscriber wish to re-- call before the answering plug AP is removed from the jack of the line circuit L,

he may do so. The subscriber, upon removing his receiver for a recall, closes a circuit path extending through through the recall relay RR extending from battery through the left hand winding of the line relay LR, normal contact of cutoff relay CO through the calling subscribers substation, tip contact of the jack J and plug AP, alternate contact 32 of relay LD through the lower winding of said recall relay RR and the normal contact 33of control relay OR. to ground. The subscriber upon removing his receiver also closes a circuit through the high resistance winding of the line relay LR, this circuit extending from battery through the left hand Winding of the relay LR, normal contact 30 of the cut-off relay CO, through the calling subscribers substation, normal contact 31 of relay CO and through the high resistance right hand winding of the relay LR to ground. gize at this time owing to thelow resistance the recall relay RR and owing to the specialadjustment of contact 34: of relay HR. The relay RR is so adjusted that upon the first slight movement of its armature its contact 34 is closed before its other contacts are moved. The relay RR, upon energizing, closes a locking circuit for itself extending from battery through its upper winding, its alternate contact 34, normal contact 26 of relay AT, alternate contact 28 of relay AS and alternate contact 13 of relay OS to ground. The relay RR also closes an energizing circuit for the cut-oil relay C0 of the recalling subscribers line. This circuit extends from ground through the winding of said cut-off relay, sleeve con ductor of jack J and plug AP, alternate energizing,

contact 3 of relay LD, alternate contact 36 of-recall relay RR and through the resistance 35 to battery.

disconnects the line relay LR from the subscribers line circuit before energize before it de-energizes.

relay RR, upon de-energizing, opens the cirit has had time toenergize and cause the line signals S to be operated. IA further result due to the energizing of the recallrelay RR is to flashthe supervisory lamp AL. The flash circuit for the supervisory lamp AL extends from battery t rough the said lamp AL,-alternate contact '29 of the recall relay RR and through the interrupter I to ground. The operator, upon noting the flashing of the answering supervisory lamp AL, removes the calling plug CP from the jack J thereb allowing the calling sleeve supervisory re ay CS to de-energize. The relay C'S, in circuits for answering sleeve supervisory re ay AS, testing relay TR, recall relay RR and connect relay LD is made slightly slow-acting to allow relays AS, TR and RR to de- The recall cuit of the supervisor lamp AL at its alter} nate contact 29. Lin disconnect relay LD,

The line; relay LR does not ener- The cut-off relay, upon -a multip upon de-energlzing opens the lock-- link disconnect relay LD. The link disthe answering sleeve supervisory relay AS to the sleeve conductor of the answering plug AP in the same manner as hereinbefore described. The link disconnect relay LD' upon de-energizing, also connects the talking conductors of the answering plug AP to the strands of the link circuit C. The recall is then handled by the operator in the same manner as previouslydescribed for handling an original call.

Assuming now that the conversation has been terminated, that the calling subscriber A and called subscriber B have replaced their receivers, and that a second operator has received a call for the calling subscriber A, the operator first tests the line of the subscriber A and finding it idle inserts the calling plug of a cord circuit in to'a jack J connected to the line circuit of subscriber A. Upon inserting the calling plug of the second operators link circuit into the jack 'J, an energizing circuit is closed through the control relay GB of the cord circuit C. This circuit extends from battery through the calling sleeve supervisory relay of the second operators the calling plug,.the sleeve of the jack J, sleeve of the answering plugAP of cord circuit C, alternate contact 3 of the link disconnect relay LD, normal contact 36 of recall relay RR and through the winding of control relay CR to ground. The control relay CR energizes over this circuit and removesground from "the lower winding of the recall relay RR so that when the second operator applies ringing current to the tip conductor of the callin plug GP, it will not cause the recall relay fi-R to be operated to cause the answering supervisory lamp AL to signal a false recall. w

Assuming now that a connection has been established, if an operator should attempt to listen in upon a busy line by inserting the answering plug of an idle link circuit into e jack of the busy line and then cord circuit, the sleeve of touch the tip of another answering or calling plug to the sleeve of the busy line in an attempt to energize the answering sleeve supervisory relay AS to connect the operators set 0 with the strands of the cord circuit that she has connected to the busy line, she will find that she will be unable to energize the supervisory relay AS to connect her set 0, as ground is normally disconnected from the tip conductors of both the answering and calling plugs.

In working'out my nvention I'have cminsec /i ployed preferred circuit arrangements, all of which go to make an efiicient operating system but it is to be understood that changes and modifications may be readily made without departing from the spirit and scope of my invention. Therefore, l do not desire to be limited to the exact arrangement shown lltl Elli

' automatic means for operating said supertill till

visory signal and for placing the subscribers line in condition to be called when the subscriber signals for disconnection, and means controlled by a single actuation of the call initiating apparatus at the subscribers substation for intermittently operating the said supervisory signal.

2. A telephone system including a subscribers telephone line, a link circuit for connection to said line to extend a call therefrom, a signal individual to said link circuit adapted to be operated to denote a recall, and means responsive to the connection of a second link circuit to said line as a called line for removing the substation control of said signal.

3. A telephone system including a subscribers telephone line, a link circuit for connection to said line to extend a call there from, recall apparatus individual to said link circuit for denoting recalls, and means for rendering said apparatus unresponsive to substation control when a second link circuit is connected to said line as a called line prior to the disconnection of said first link circuit from said line.

4. In a telephone system a subscribers line, a'plurality of terminals for said line, a linkcircuit adapted to be connected to said line for extending a call, recall apparatus individual to said link circuit and con-.

trollable by the subscriber, means for making said line busy when said link circuit is connected to the said line, means for removing the busy potential when disconnection is desired, and a relay for removing the substation control of said'recall apparatus so that the line may be connected with as a called line.

5. A telephone system including a. sub scribers telephone line, a pluralit of terminals for said line, a link circuit or extending a connection from said line and for placing a busy potent1al-upon said termlnals, recall apparatus individual to said link circuit, subscriber controlled means for removing the busy potential from said terminals, and means responsive to the connection of a second link circuit to one or said terminals forrendering said recall apparatus ineffective.

6. A telephone system including a subscribers telephone lme, a plurality of terminals for said line, alink circuit for extending a connection from said line, recall apparatus individual to said link circuit, and means responsive to the connection of a second link circuit to one of said terminals for removing the substation control of said recall apparatus.

-7. A telephone system including a subscribers telephone line provided with a plurality of multiple terminals, a link circuit provided with a connection terminal for connection to one of said terminals for extending a call from said line, subscribercontrolled means for removing the busy potential from said line when said subscriber signals for disconnection, and a supervisory signal for said link circuit adapted to be intermittently operated to denom recall responsive to a single actuation of the sub-- scribers substation equipment 8. A telephone system includlng a subscribers telephone line, multiple line terminals and line signals for said line, a link circuit for connection to said line and for placing a busy potential upon said multiple terminals, subscriber controlled means for removing said busy potential, a signal associated with said link circuit, and means for automatically intermittently operating said signal when a recall is initiated.

9 A telephone system including a subscribers telephone line, multiple line terminals and line signals for said line, a link circuit for connection to said line and for placing a busy potential upon said multiple terminals, subscriber controlled means for removing said busy potential, a signal associated with said link circuit, and means for intermittently operating said signal responsive to a single actuation of the call initiating apparatus at the subscribers substation when a. recall is initiated.

10. A telephone system including a subscribers telephone line, multiple line terminals for said line, a link circuit for oonnection to said line, a signal associated with said link circuit, subscriber controlled means board, operators link circuits for connection to said line, automatic means for preventing .the operative connection of more than one of said link circuits to said line at one time in answering a call, a signal for said link circuit, and apparatus associated with said llIlk circuit for causing said signal to be inter-' nection to said line, a signal forsaid link circuit, automatic means for disconnecting said line from the talking strands of said link circuit when disconnectionis signaled for, and means responsive to a unitary actuation of the subscribers substation equipment for intermittently operating said signal when a recall is signaled for.

14. A telephone system including a calling subscribers telephone line, a link circuit for connection to said line for extending a call therefrom, a signal for said link circuit, means responsive to .a removal of the receiver at the subscribers substation for causing an intermittent operation of said signal to denote a recall, and automatic means for disassociating the subscribers line and the talk-- ing strands of said link circuit.

15. A telephone system including a subscribers telephone line, a link circuit for connection to said line for extending a call therefrom, a signal for said link circuit adapted to be intermittently operated by a unitary. actuation of the call initiating apparatus at the subscribers substation to denote a recall, and means responsive to the connection of a second link circuit to said subscribers line as a called line for rendering ineflective' the substation controlof said signaL. A

16. A telephone system including a subscribers telephone line, a link circuit for connection tosaid line, a supervisory signal for said link circuit, a supervisory relayfor ,actuating said supervisory signal adapted to be controlled from the subscribers substation, electromagnetic disconnect means for removing the substation control of said supervisory relay, and a second relay responsive to the removal of the receiver at the substation for causing the intermittent operation of said supervisory signal;

17. A. telephone system'including a subscribers telephone line, a link circuit .for connection to said line, a supervisory signal for said link circuit, asupervisory relay adapted to be controlled over the subscribers -line for cont-rolling the said supervisory signal, electromagnetic disconnect means for removing the substation control of said supervisory relay, a relay responsive to the removal of the receiver at the subscribers substation for causing the intermittent operation of said supervisory signal, and means responsive to the connection of a second link circuit to the said telephone line for removing the substation control of said second relay. J y

18. A telephone system including a subscribers line, a link circuit for extending a call from said line, a signal individual to said link circuit under substation control, and means for permitting a second link circuit to connect to said line and for removing the substation control of said signal.

19. A telephone system including a subscribers telephone line, a link circuit for connection to said line to extend a call therefrom, a supervisory signal individual to saidlink circuit, substation controlled means 7 for operatively disassociating said link circuit. from said subscribers line, and substation controlled means for causing an intermittent operation of said supervisory signal.

20. A telephone system including a subscribers telephone line provided with multipleanswering terminals, groups of opera.- tors link circuits, a supervisory signal for each of said link circuits, means for .plfeventing the operative connection of more than one of said link circuits to said subscribers line when answering a call, and automatic means controlled over the callingsubscribers line for intermittently'operating the superviso'ry signal of the link circuit connected to the subscribers line. i

21. A telephone system including a subscribers telephone line, a link circuit for connection to said line to extend a call therefrom, a supervisory signal individual to said ,link circuit, substation controlled means for operatively disassociating said link circuit from said subscribers line, and substation controlled means for operating said supervisory signal. to denote a recall.

22. In a telephone system, "the combination ofa main station, a plurality of telephone lines leading to the main station, substation apparatus on each telephone line, line signalling mechanism for each telephone line, cut-ofi relays for disassociating said mechanism from its associate telephone line, one of said cut-ofl relays being associated with each telephone line, a cord circuit at the main station and mechanism to connect said cord circuit to a telephone line, a circuit for the cut-off relay associated with thetelephone line to which the cord is connected completed to cause-the energization of said cut-off relay when the cord is conrsaaori nected to the line, means controlled by the subscriber for causing the de-energization the re-energization' of said cut-oil relay when the subscriber signals for a recall.

24. A telephone system including a subscribers telephone line terminating'in a jack at the central exchange, a cut-oil relay for said line, a link circuit provided with a plug for insertion in said jack, a circuit for the cut-off relay completed in response to the insertion of said plug in said jack, subscriber-controlled means for de-energizing said cut-oft relay when the subscriber signals for disconnection and for causing the re-energization of said cut-0d ,relay when the subscriber signals for a recall, and a signal for said cord circuit adapted to be intermittently operated when the subscriber signals for a recall. I I

25. A telephone system including a subscribers telephone line terminating in a jack at the central exchange, a cut-off relay for said line, a link circuit provided with a plug for insertion in said jack, a circuit for the cut-off relay completed in response to the insertion of said plug in said jack subscriber-controlled means for tie-energiz ng said cut-off relay when the subscriber slignals for disconnection and for causing the re-energization of said cut-off relay when the subscriber signals for a recall, and operator.-v controlled'means for preventing a subscriber" from re-energizing said cut-oil relay.

26. A telephone system including a subscribers telephone line terminating in a jac at the central exchange, a cutoff relay for said line, a link. circuit provided with a plug for insertion in said jack, a circuit for the cut-oil relay completed in response to the.

insertion of said plug in said jack, subscriber-controlled means for ole-energiz ng said cut-0d relay when the subscriber signals for disconnection, a supervisory signal individual to said link circuit, and subscriber-controlled means for automatically flashing said supervisory signal when a recall is signaled for.

2?. A telephone system including a subscriber s telephone line terminating in a jack at the central exchange, a cut-oft relay "for said line, a link circuit provided with a plug 'scribers line when answerin for insertion in said jack, a circuit for the cut-off relay completed .in response to the insertion of said plug in said jack, subscriber-controlled means for de-energizing said cut-ofi relay when the subscriber signals for disconnection, a supervisory si nal individual to said link circuit, subscri er,- controlled means for automatically flashing said supervisory signal when a recall is signaled for, and operator-controlled means responsive to the. connection of a second link circuit .to said subscribers line for prevent ing a subscriber from intermittently operating said supervisory signal.

28. A telephone system "including a subscribers-telephone line, a link circuit for connection to said line, a supervisory signal for said link circuit, a supervisory relay for actuating said supervisory signal adapted to be controlled from the subscribers substation, substation-controlled disconnect means for removing the substation control of said supervisory relay, a second relay responsive to the removal of the receiver at the substation for causing the intermittent operation of said supervisory signal, and operator-controlled means for preventing the subscriber from operating said second relay. 29. A telephone system including a subscribers telephone line terminating in a jack at the central exchange, a cut-oft relay for saidline, a link circuit provided with a plug for insertion in said jack, a circuit for the cut-off relay completed in response to the insertion of said plug in said jack, subscriber-controlled means for de-energizing said cut-off relay when the subscriber sig nals for disconnection and for causing the re-energization of said cut-0d relay when the subscriber signals for a recall, and means responsive to the connection of a second link circuit to said telephone line for re-energizing said cut-ofi relay and for thereafter preventing the subscriber from -de-energizing'said cut-oii' relay.

k ators link circuits a su ervisor si ial for 9 P Y g1 each of said link circuits, means for preventing the operative connection of more than one of said link circuits to said suba call, automatic means controlled over t e calling subscribers line for intermittently operating the supervisory si ial of the link circuit connected to the su scribers line and means responsive to the connecticn'or a second link circuit to 'said telephone line for removing the control of the supervisory 'signal from the subscriber.

31. A telephone system including a sub scribers telephone line provided with multiple answering terminals, groups of op reach of said link circuits, means for preventing the operative connection of more than one of said link circuits to said subscribers line when answering a call, subscriber-controlled means for operatively disassociating the subscribers line from the connected link circuit. and automatic means controlled over the calling subscribers line for intermittently operating the supervisory signal of the link circuit connected to the subscribers line.

32. A telephone system including a subscribers telephone line provided with multiple answering terminals, groups of operators link circuits, a supervisory signal for each of said link circuits, means for preventing the operative connection of more than one of said link circuits to said subscribers line when answering a call, auto-' matic means controlled over the calling sub-' scribers line for intermittently operating the supervisory signal of the link circuit connected to the subscribers line, and auto matic means for connecting and disconnecting an operators telephone set andthe said link circuit.

33. In a telephone system, the combination of'a main station, a calling telephone line, substation apparatus includingaswitch on the calling line, line signaling-mechanism for said telephone line, a cut-01f relay for said telephone line adapted when enerw gized to disassociate said line signaling mechanism from the line, a cord circuit at the main station, a switch for connecting the cord circuit to the telephone line, a circuit for said cut-off relay controlled by said switch and completed when said switch is operated, to cause the energization of the cut-off relay, a second relay controlled by the switch at the subscribers station and contacts in the circuit ofthe cut-off relay controlled by said subscriber-controlled relay, said second relay causing the opening of the circuit and the de-energizationof the cut-01f relay when the subscriber retires, and means for recompleting such circuit when the subscriber initiates a recall to causea second energization of saidcut-oif relay.

34., A telephone system including a subscribers telephone line terminating in a jack, a cut-off rela for said line, a connecting circuit provided with a lug for insertion in said ,jack, a circuit or the cutoff relayresponsive to the insertion of a plugin the jack, subscriber-co'ntrolled means for de-energizing said cut-ofi relay,

' and subscriber controlled means for re-en- I mg circuit rovided with a plug for insertion in sai jack, a circuit for; the cut-off relay responsive to the insertion of a plug in means for operating the said relay, andsuba scriber controlled means for again seizing said connecting circuit.

37. A telephone system including a calling subscribers line and a called subscribers line, an operators link circuit for use in connecting said subscribers lines, electromagnetic means in said link circuit for dis connecting one of said subscribers lines from the link circuit, subscriber controlled means for operating said electromagnetic means, and subscriber controlled means for again seizing said link circuit.

38. A telephone system including a calling subscribers line and a called subscriberls line, an operators' link circuit for use in connecting said subscriberslines, subscriber controlled means for disconnecting one or said lines from said link circuit, and subscriber controlled means for again seizing said link circuit.

39. A telephone system including a calling subscribers-line and a called subscribers line, an operators link circuit for use in con,- necting said subscribers lines, and subscriber controlledmeans for operatively dis associating one of the subscribers lines from the said link circuit and for again seizing said link circuit.

40. A telephone system including a calling subscribers line and a called. subscribers line, an operators link circuit for use in establishing connection between said lines, and subscriber controlled means for operatively freeing one of said subscribers lines from said link circuit when he signals for disconnection and for again operatively as sociating said subsc-ribers line with the link circuit when hesignals for a recall.

' 41. A telephone system including a calling subscribers line and a called subscribers line, an operators link circuit for use in establishing connection between said lines, subscriber controlled means for o eratively freeing one of said lines from sai link circuit when he signals for disconnection, and subscribercontrolled means for again seiz ing said link circuit whenlthe subscriber attempts ,to initiate a recall and extend another connection.

- 42. A telephone system including a calling subscribers line and a called subscribers line, an operators link circuit for use in establishing connection between said subsoribers l1nes,'a relay for rendering a-c1rcuit inoperative, means controlled over a subscribers line for efiecting said relay and for operatively freeing one of the subscribers lines from the link circuit when said subscriber signals 'for disconnection, and means controlled over the, said subscribers line for again affecting said relay when the subscriber signals for a recall. 43. A telephone system including-a calling subscribers line, a called subscribers line, an operators link circuit for use in establishing a connection between said subscribers lines, a relay controlling a circuit, and means controlled over one of the subscribers lines for affecting said relay and for operatively disconnecting the subscribers line from the link circuit when the subscriber signals for adisconnectiomand for again afi'ecting said relay when the subscriber signals for a recall.

44. A telephone system including subscribers telephone lines, an operators circuit for use in interconnecting said lines, a disconnect relay in said circuit for disconnecting one of said subscribers lines from the other of said subscribers line's, subscriber controlled means for operating said relay, and subscriber controlled means for again seizing said connecting circuit.

1 45. A telephone system including a calling subscribers line and a called subscribers line, an operators link circuit for use in connecting said subscriberstlmes, electromagnetic means insaid link circuit for disconnecting, one of said subscribers lines from the other of said subscribers lines,.sul 0 scriber controlled means for operating sald electromagnetic means, and subscriber controlled means for again seizing said link circuit. a

46. A telephone system including a calling subscribers line and'a called subscribers line, an operators link circuitifor use in connecting said subscribers lines,- subscriber controlled means for disconnecting oneoi. said lines from the other of said lines, and subscriber controlled means for again seizing said link circuit and for affecting a signal.

47. A telephone system including a calling the other of said subscribers lines, and for said subscribet lines again seizing said link circuitand operating a signal. 48. A telephonesystem including a calling subscribers line and a called subscribers call and extend another connection and for affecting a signal to said linkcircuit.

49. A telephone system including a calling subscribers. line and a called subscribers line, an operators link circuit for use in establishing connection between said subscribers line, a relay for rendering a circuit inoperative, means controlled over a subscribersline for affecting said relay and for operatively freeing one of said subseribers lines from the. other of said subscribers lines when said subscriber signals for disconnection, and meanslcontrolled over the said subscribers line for again afi'ecting' said relay .when the subscriber signals for a recall. 5 0. In a telephone system, the combination of a main station, a calling telephone line,

I substation apparatus including a switch on between said lines,

tion, a switch for connecting the cord circuit to the telephone line, a circuit for said cutoff relay controlled by said switch and completed when said switch is operated, to cause the energization of the cut-off relay, meansincluding a second relay controlled by the switch at thesubscribers station and contacts in the circuit of the cut-off relay controlled by said subscriber-controlled relay for causing the opening of the circuit and the de-energization of the cut-off relay when the subscriber retires and recompleting such circuit when the subscriber initiates a recall tocause a second energization of said cut-off relay.

Signed b me at Chicago, in the county of Cook and tate of Illinois, in the presence of two witnesses.

. HIRAM D. CURRIER.

Witnesses:

G. A. YANocHoWsKI, B. OlB IEN. 

